1. Field of the Invention
The present invention relates to a heat exchanger having a heat exchange core and heat transfer medium introduction and discharge tanks, and more specifically, to a heat exchanger suitable for use as an intercooler.
2. Description of Related Art
A heat exchanger is known, which has a heat exchange core consisting of alternately stacked, heat transfer tubes and fins and in which a introduction tank for introducing heat transfer medium into the heat exchange core and a discharge tank for receiving the heat transfer medium discharged from the heat exchange core are attached to the heat exchange core. For example, such a heat exchanger is described in Japanese Patent Publication No. JP-A-5-1896. Such a heat exchanger may be utilized in various fields, including as a heat exchanger used in a refrigeration circuit for vehicles or as an intercooler for cooling charged gas from a turbo-charger or a supercharger. In such a heat exchanger, both tanks generally are formed from a metal, for example, as described in Japanese Patent Publication No. JP-A-9-79787, or from a resin, for example, as described in Japanese Patent Publication No. JP-A-2002-195043, and both tanks are made of the same material.
Generally, when a heat exchanger is mounted on a vehicle, improved performance may be desired in properties, such as pressure resistance, thermal resistance, and sound-proofing capability when compared with heat exchangers used in other fields. For example, in an intercooler, in which the heat transfer medium introduction tank and the discharge tank are attached to a heat exchange core consisting of heat transfer tubes and fins disposed alternately, a high thermal resistance is desired for the introduction tank because a high-temperature, charged gas is introduced to that tank. Therefore, both the introduction tank and the discharge tank have been made of expensive material exhibiting high thermal resistance, thereby achieving a desired thermal resistance for the introduction tank. However, with respect to the discharge tank of such an intercooler, an enhanced sound-proofing capability is desired, rather than high thermal resistance as the introduction tank. If the discharge tank also is made of the same expensive material having a high thermal resistance, the cost of manufacturing the intercooler may increase. Moreover, the properties desired for the introduction tank and the discharge tank, respectively, may not be satisfied sufficiently.
In such a situation, the discharge tank may be coated with a covering material formed from a rubber or a resin in order to improve the sound-proofing capability of the discharge tank. If such a cover material is provided, the cost of the intercooler also may increase because the number of heat exchanger parts and the number of steps in the manufacturing process increase.